Japanese patent application laid-open No. 2-73229 (1990) discloses a structure of liquid-crystal display panel where thermosetting sealing agent is used in side and ultraviolet-activated sealing agent is used outside.
The glass transfer temperature of organic materials used for organic thin film EL device is around 100.degree. C., and it is generally necessary to apply a temperature of higher than 100.degree. C. for several hours to harden thermosetting adhesives. Therefore, it may cause the deterioration in luminous characteristic.
Also, in organic thin film EL device, when bonding a glass substrate and a sealing cap using an ultraviolet-activated adhesive, hardening the adhesive, and then thermo-compression bonding a flexible print-circuit board, there may occur peeling between the hardened adhesive and the glass substrate due to a difference in thermal expansion coefficient between the hardened adhesive and the glass substrate. For example, when applying a temperature of higher than 200.degree. C. at a distance of less than about 5 mm from the hardened adhesive, peeling is likely to occur between the hardened adhesive and the glass substrate.
When the distance between the flexible print-circuit and the ultraviolet-activated adhesive is widened to solve the above problem, there occurs the problem that the display area is reduced.
Japanese patent application laid-open No.62-231927 (1987) discloses a method that, in liquid-crystal display panel, temporary bonding is conducted by irradiating ultraviolet rays on part of sealing material, then hardening all parts thereof.
Also in organic thin film EL device, a method that part of the same adhesive is hardened, thermo-compression bonding the flexible print-circuit board, then hardening all parts of the adhesive as disclosed in Japanese patent application laid-open No.62-231927 can be imagined.
However, when unalteredly applying the technique disclosed in Japanese patent application laid-open No.62-231927 to the organic thin film EL device, different stresses, which are caused by the contraction of adhesive due to its hardening, are applied to first and second adhering parts. Therefore, the adhesive power is more reduced than the case that all part of adhesive is hardened at once.